Biology subjects

Ng, T. F. F.

Publications and source records attributed to Ng, T. F. F..

6 recordsLinked to original sources

bioRxiv2022

Type-specific EV-D68 real-time RT-PCR assay for the detection of all extant enterovirus D68 strains

Enterovirus D68 (EV-D68) has caused recurring respiratory disease outbreaks in the United States since 2014. The dominant circulating EV-D68 strain has evolved from clade B1 to the more recent B2 and B3 clades. As recurrent outbreaks and continued virus evolution are expected for EV-D68, a robust real-time PCR assay that detects known strains as well as potential emerging strains is critical for national surveillance and clinical diagnostics. We describe a type-specific EV-D68 real-time RT-PCR (rRT-PCR) assay termed CDC2022, which targets sequences encoding conserved amino acid regions of all extant EV-D68 strains. We targeted three motifs conserved among all strains in the last 60 years. The assay achieved 100% (270/270) sensitivity and 100% (344/344) specificity when tested with a collection of 613 respiratory specimens, compared to the gold-standard EV semi-nested VP1 PCR and sequencing assay (snPCR/Seq). CDC2022 gave negative results with 289/289 non-target viruses, including 104 EV A-D isolates, 165 rhinovirus (RV) isolates or clinical specimens, and 14 other common respiratory viruses. The assay can detect as few as 0.28 CCID50 per reaction. An in silico "phylo-primer-mismatch" analysis was performed to visualize primer/probe mismatches and to compare CDC2022 with other EV-D68 rRT-PCR assays, including the previous CDC assay (CDC2015) developed in 2014 for clade B1 strains. It showed that CDC2022 has the fewest primer/probe mismatches among all assays analyzed and is suitable for all clades. We additionally tested 11 EV-D68-positive clinical specimens from 2022 that were confirmed by snPCR/Seq, and all were detected. CDC2022 assay could provide a critical tool for molecular surveillance of EV-D68.

microbiology↗

bioRxiv2019

The effect of variant interference on de novo assembly for viral deep sequencing

Viruses have high mutation rates and generally exist as a mixture of variants in biological samples. Next-generation sequencing (NGS) approach has surpassed Sanger for generating long viral sequences, yet how variants affect NGS de novo assembly remains largely unexplored. Our results from >15,000 simulated experiments showed that presence of variants can turn an assembly of one genome into tens to thousands of contigs. This \"variant interference\" (VI) is highly consistent and reproducible by ten most used de novo assemblers, and occurs independent of genome length, read length, and GC content. The main driver of VI is pairwise identities between viral variants. These findings were further supported by in silico simulations, where selective removal of minor variant reads from clinical datasets allow the \"rescue\" of full viral genomes from fragmented contigs. These results call for careful interpretation of contigs and contig numbers from de novo assembly in viral deep sequencing.

microbiology↗

bioRxiv2019

Comparison of Illumina MiSeq and the Ion Torrent PGM and S5 platforms for whole-genome sequencing of picornaviruses and caliciviruses

Next-generation sequencing is a powerful tool for virological surveillance. While Illumina(R) and Ion Torrent(R) sequencing platforms are used extensively for generating viral RNA genome sequences, there is limited data comparing different platforms. We evaluated the Illumina MiSeq, Ion Torrent PGM and Ion Torrent S5 platforms using a panel of sixteen specimens containing picornaviruses and human caliciviruses (noroviruses and sapoviruses). The specimens were processed, using combinations of three library preparation and five sequencing kits, to assess the quality and completeness of assembled viral genomes, and an estimation of cost per sample to generate the data was calculated. The choice of library preparation kit and sequencing platform was found to impact the breadth of genome coverage and accuracy of consensus viral genomes. The Ion Torrent S5 outperformed the older Ion Torrent PGM platform in data quality and cost, and generated the highest proportion of reads for enterovirus D68 samples. However, indels at homopolymer regions impacted the accuracy of consensus genome sequences. For lower throughput sequencing runs (i.e., Ion Torrent 510 or Illumina MiSeq Nano V2), the cost per sample was lower on the MiSeq platform, whereas with higher throughput runs (Ion Torrent 530 or Illumina MiSeq V2) the cost per sample was comparable. These findings suggest that the Ion Torrent S5 and Illumina MiSeq platforms are both viable options for genomic sequencing of RNA viruses, each with specific advantages and tradeoffs.

microbiology↗

bioRxiv2019

Serological and metagenomic interrogation of cerebrospinal fluid implicates enteroviruses in pediatric acute flaccid myelitis

BackgroundSince 2014, the United States has experienced a biennial spike in pediatric acute flaccid myelitis (AFM). Epidemiologic evidence suggests non-polio enteroviruses (EVs) are a potential etiology, yet EV RNA is rarely detected in cerebrospinal fluid (CSF) and only inconsistently identified from the respiratory tract, serum, or stool.\n\nMethodsWe interrogated CSF from children with AFM (n=42) and pediatric controls with other neurologic diseases (OND) (n=58). Samples were incubated with T7 bacteriophage expressing 481,966 sixty-two amino acid peptides with a fourteen amino acid overlap tiled across all known vertebrate virus and arbovirus genomes, an adaption of the VirScan method. Antibody-bound phage were deep sequenced to quantify enriched peptides with normalized counts expressed as reads per hundred thousand (rpK). EV antibody findings were confirmed with ELISA using whole viral protein 1 (VP1) from contemporary enterovirus (EV) A71 and D68 strains. Separately, metagenomic next-generation sequencing (mNGS) of CSF RNA, both unbiased and with targeted enrichment for EVs, was performed.\n\nResultsThe most significantly enriched viral family by VirScan of CSF in AFM versus OND controls was Picornaviridae (mean rpK 11,266 versus mean rpK 950, p-adjusted < 0.001, Wilcoxon signed-rank test with Bonferroni adjustment). Enriched Picornaviridae peptides belonged almost entirely to the genus Enterovirus. The mean EV VP1 ELISA signal in AFM (mean OD 0.51) was significantly higher than OND controls (mean OD 0.08, p-value < 0.001, Mann-Whitney test). mNGS did not detect additional enterovirus RNA in CSF.\n\nConclusionDespite the rare detection of EV RNA in the CNS of patients with AFM, a pan-viral serologic assay identified high levels of CSF EV antibodies in AFM CSF compared to CSF from OND controls. These results provide further evidence for a causal role of non-polio enteroviruses in AFM.

microbiology↗

bioRxiv2018

Complete genome sequence of a divergent strain of Tibetan frog hepatitis B virus associated to concave-eared torrent frog Odorrana tormota

The family Hepadnaviridae is characterized by partially dsDNA circular viruses of approximately 3.2 kb, which are reverse transcribed from RNA intermediates. Hepadnaviruses (HBVs) have a broad host range which includes humans (Hepatitis B virus), other mammals (genus Orthohepadnavirus), and birds (Avihepadnavirus). HBVs host specificity has been expanded by reports of new viruses infecting fish, amphibians, and reptiles. The tibetan frog hepatitis B virus (TFHBV) was recently discovered in Nanorana parkeri (Family Dicroglossidae) from Tibet. To increase understanding of hepadnavirus in amphibian host, we identified the full-length genome of a divergent strain TFHBV-Ot associated to the concave-eared torrent frog Odorrana tormota (Family Ranidae) from China by searching deep sequencing data. TFHBV-Ot shared the genomic organization and a 76.6% overall genome nucleotide identity to the prototype TFHBV associated to N. parkeri (TFHBV-Np). TFHBV-Ot amino acid pairwise identity with TFHBV-Np predicted gene products ranged between 63.9% and 77.9%. Multiple tissue/organ specific RNAseq datasets suggest a broad tropism of TFHBV including muscles, gonads and brains. In addition, we provide for the first time evidence of virus derived small RNA from an amphibian hepadnavirus, tentatively enriched in 19-20 nt species and cytidine as first base. The results presented here expand the genetic diversity and the host range of TFHBV to Ranidae frogs, and warrant investigation on hepadnaviral infection of amphibian brains.

microbiology↗

bioRxiv2018

Adomaviruses: an emerging virus family provides insights into DNA virus evolution

Adenoviruses, papillomaviruses, and polyomaviruses are collectively known as small DNA tumor viruses. Although it has long been recognized that small DNA tumor virus oncoproteins and capsid proteins show a variety of structural and functional similarities, it is unclear whether these similarities reflect descent from a common ancestor, convergent evolution, horizontal gene transfer among virus lineages, or acquisition of genes from host cells. Here, we report the discovery of a dozen new members of an emerging virus family, the Adomaviridae, that unite a papillomavirus/polyomavirus-like replicase gene with an adenovirus-like virion maturational protease. Adomaviruses were initially discovered in a lethal disease outbreak among endangered Japanese eels. New adomavirus genomes were found in additional commercially important fish species, such as tilapia, as well as in reptiles. The search for adomavirus sequences also revealed an additional candidate virus family, which we refer to as xenomaviruses, in mollusk datasets. Analysis of native adomavirus virions and expression of recombinant proteins showed that the virion structural proteins of adomaviruses are homologous to those of both adenoviruses and another emerging animal virus family called adintoviruses. The results pave the way toward development of vaccines against adomaviruses and suggest a framework that ties small DNA tumor viruses into a shared evolutionary history. Author SummaryIn contrast to cellular organisms, viruses do not encode any universally conserved genes. Even within a given family of viruses, the amino acid sequences encoded by homologous genes can diverge to the point of unrecognizability. Although members of an emerging virus family, the Adomaviridae, encode replicative DNA helicase proteins that are recognizably similar to those of polyomaviruses and papillomaviruses, the functions of other adomavirus genes have been difficult to identify. Using a combination of laboratory and bioinformatic approaches, we identify the adomavirus virion structural proteins. The results link adomavirus virion protein operons to those of other midsize non-enveloped DNA viruses, including adenoviruses and adintoviruses.

microbiology↗